This Report presents a state-of-the-art implementation of lossless image compression algorithm LOCO-R, which is based on the LOCO-I (low complexity lossless compression for images) algorithm developed by weinberger, Seroussi and Sapiro, with modifications and betterment, the algorithm reduces obviously the implementation complexity. Experiments illustrate that this algorithm is better than Rice Compression typically by around 15 percent.

METHODOLOGY:

The LOCO-R algorithm is based on predictive compression. During compression, the pixels of the image are processed in raster scan order. Specifically, y is incremented through the range[O,ht-l], and for each y value, x is incremented through the range[O,wd-l]. (Thus, the y dimensions the slowly varying dimension.)The first two pixels, with coordinates (0,0) and (1,0), are simply put into the output bit stream encoded. For all other pixels of the image, the processing that occurs can be conceptually divided into four steps:

Classify the pixel into one of several contexts according to the values of (usually 5) previously encoded pixels.

Estimate the pixel value from (usually 3) previously encoded pixels, and add a correction( called the bias), which depends on the context.

Map the difference between the estimate and the actual pixel value to a non-negative integer, and encode this integer using Golomb's variable length codes.